Abstract

Deinonychosaurian theropods, the dinosaurian sister group of birds, are characterized by a large raptorial claw borne on a highly modified second digit that was thought to be held in a retracted position during locomotion. In this study, we present new trackway evidence for two coeval deinonychosaurian taxa from the Early Cretaceous of Shandong, China that indicate a hitherto unrecognized body size diversity for this period and continent. These fossil tracks confirm diversity and locomotory patterns implied by phylogeny and biogeography, but not yet manifested in the body fossil record. Multiple parallel and closely spaced trackways generated by the larger track maker provide the best evidence yet discovered for gregarious behavior in deinonychosaurian theropods.

Keywords

Deinonychosaur Cretaceous Footprint Gregariousness China Locomotion

Communicated by: G. Mayr

The online version of this article (doi:10.1007/s00114-007-0310-7) contains supplementary material, which is available to authorized users.

Notes

Acknowledgments

This study was supported financially in part by National Natural Science Foundation of China grant 40572011 to R-H. L. Additional support was provided by the University and Society Collaboration of the Japanese Ministry of Education, grant-in-aid 1183303, 1999-2000 to M. M., and by the University of Colorado at Denver Dinosaur Tracks Museum to M. G. L. M.A.N. and P.J.M. were both supported by US National Science Foundation AToL EAR 0228607 and by the AMNH and FMNH, respectively. S. Harris produced the movie and M. Ellison photographed the seriema foot for Fig. 4.

Supplementary material

S1Supplementary Movie of 3D views of Dromaeopodus paratype: a movie providing a 3D range of views of a digital rendering of the paratype Dromaeopodus shandongensis track (CU 214.112, replica of left pes) is available with the online version of this article at: (MOV 2.84 MB)